The present invention relates to the lighting arts. It especially relates to illuminators, spot lights, overhead lamps, and other light sources that employ a plurality of light emitting diodes, and to reflectors for such light sources, and will be described with particular reference thereto. However, the invention will also find application in conjunction with light sources that employ a plurality of light emitting elements other than light emitting diodes, such as miniature lamps, semiconductor lasers, and the like. The invention will still further find application in conjunction with reflectors for such other light sources.
Conventional parabolic reflectors are designed for use in conjunction with a single, high brightness light emitting element such as an incandescent filament. The high brightness light emitting element is placed at a focal point of the reflector, and the parabolic reflector geometry causes light rays emanating from the focal point to be directed outward from the reflector opening or aperture as a generally collimated beam of light. Some beam divergence, which may be desirable for certain applications, can be obtained by arranging the incandescent filament in a “defocused” position a selected distance away from the focus. Moreover, a spherical reflector or other generally collimating reflector may be used instead of the parabolic reflector. A spherical reflector does not provide complete collimation, and so the beam produced using a spherical reflector has some divergence.
Existing light emitting diodes are generally not as bright as incandescent filaments. To produce a high brightness light source using light emitting diodes, it is generally advantageous to employ a plurality of light emitting diodes whose combined light output is comparable to or exceeds the output of a single high brightness incandescent filament. Replacing the incandescent filament with light emitting diodes has certain advantages, such as improved distribution of heat dissipation, higher reliability, and improved ruggedness of the light source.
However, the parabolic reflector commonly used for incandescent lamps is difficult to adapt for use with a plurality of light emitting elements. This is because it is difficult to arrange all the light emitting elements close to the focal point of the parabolic reflector. Those light emitting elements that are arranged some distance away from the reflector focus are not well collimated by the parabolic, spherical, or other generally collimating reflector.
One approach to addressing this problem is to provide a separate parabolic reflector for each light emitting diode. Each light emitting diode is arranged at the focal point of its corresponding reflector, so that the light from each light emitting diode is formed into a collimated beam of light. However, this arrangement usually produces a granularized illumination made up of a plurality of collimated “beamlets” corresponding to the plurality of light emitting elements. Such granularized illumination may be undesirable for certain applications. Moreover, the individual reflectors are arranged in an array or other closely packed configuration to provide cumulative illumination. Such an arrangement may present manufacturing difficulties.
The present invention contemplates an improved apparatus and method that overcomes the above-mentioned limitations and others.